I think Expose is a better version of Cascade in most (not all) use cases, since you can see what's in each window. As far as I'm concerned, Expose is the best feature in Mac OS. The fluidity of swiping in different directions to get what you want between Spaces, Mission Control, and Expose, is unparalleled in any other computer platform. I've tried to setup Windows and Linux to run the same way, but it's just not the same, then I feel like I'm too restricted. I think if Linux could better copy the functionality, I'd use it daily.
I use Spaces / Mission Control / Expose so much, that I replaced my 10 button mouse for a Magic Trackpad a few years back.